SMD Soldering Using Adhesive Posts for Controlled Gap
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Solution Overview
Problem
Wave soldering is inadequate for producing good solder joints for surface mount devices (SMDs), especially non-leaded SMDs, due to insufficient and unreproducible solder coverage, leading to electrical failures and scrap parts.
Innovation Solution
A method involving the deposition of first and second adhesive volumes on an application board, where the SMD is supported by hardened first adhesive volumes to create a controlled gap, allowing molten solder to fill and secure the SMD to the board, with the gap height adjustable to ensure adequate solder coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wave soldering is used to mount SMDs, then the process is cheaper and faster, but solder coverage is insufficient and unreproducible
Solution Approach 1:
The patent applies preliminary action by depositing adhesive volumes on the application board before the soldering process. The adhesive volumes are hardened to form posts that create a controlled gap, preparing the structure in advance to ensure adequate solder coverage during the subsequent wave soldering process.
Solution Approach 2:
The patent introduces a vertical dimension by creating a gap between the SMD and the application board using hardened adhesive posts. This gap height (at least 150 or 200 μm) allows molten solder to flow underneath the SMD, providing solder coverage from below, which is the critical missing dimension in conventional wave soldering.
2Reliability
If reflow soldering is used to achieve good solder joints, then solder coverage is adequate, but the process is more time consuming and expensive
Solution Approach 1:
The patent changes the physical parameters of the soldering setup by introducing a controlled gap height (at least 150 or 200 μm) through adhesive posts. This parameter change enables wave soldering to achieve solder penetration and coverage previously only attainable through reflow soldering, allowing the use of faster wave soldering processes.
3Length of stationary object
If SMDs are placed directly on the application board, then the structure is compact, but solder coverage is insufficient
Solution Approach 1:
The patent segments the bonding function into two separate adhesive volumes: first adhesive volumes that form posts to create the gap, and second adhesive volumes that provide additional bonding. This segmentation allows the structure to maintain compactness while ensuring adequate solder coverage through the created gap.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method ensures reliable solder joints by maintaining a controlled gap height of at least 150 or 200 µm, improving solder coverage and reducing electrical failures, thereby enhancing the reliability of SMD attachment to the application board.
Implementation Method 1
depositing one or more first adhesive volumes onto the application board; hardening the one or more first adhesive volumes; depositing one or more second adhesive volumes onto the application board
Implementation Method 2
soldering the SMD to the application board by applying molten solder in the gap between the application board and the SMD
Data Source
Figure 1~3
Figure 4~5B
Figure 5C~5D
AI summary
A method of soldering a surface mount device (SMD) to an application board comprises depositing one or more first adhesive volumes onto the application board. The one or more first adhesive volumes are hardened. One or more second adhesive volumes are deposited onto the application board. The SMD is placed on the hardened one or more first adhesive volumes in contact with the one or more second adhesive volumes, wherein the SMD is supported by the hardened one or more first adhesive volumes to form a gap between the application board and the SMD. The one or more second adhesive volumes are hardened to hold the SMD to the application board. The SMD is soldered to the application board by applying molten solder in the gap between the application board and the SMD.